The last few years I have made several repairs of measuring equipment which I bought with some kind of defect.
Hameg portable Spectrum analyzer HM5033
HP8566b Spectrum analyzer
HP8672A synthesized Signal generator
Anritsu MT8212B Cell Master
HP8970A Noise Gain analyzer
HP8970B Noise Gain analyzer Error 18
A HP8672A Synthesizer with no Output and Phase Lock error